Double pole snap switch



Nov. 18, 1952 H DRESSEL 2,618,714

DOUBLE POLE SNAP SWITCH Filed Aug. 4. 1949 INVENTOR. HENRY (7. 0259354..

Patented Nov. 18, 1952 DOUBLE POLE SNAP SWITCH Henry M. Dressel, St. Marys, Pa., assignor to Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania Application August 4, 1949, Serial No. 108,526

(Cl. ZEN-67) 2 Claims.

This invention relates to electric snap switches of the bridging contact type, and more particularly to a double pole snap switch.

One of the problems in making switches for radios and television is to provide reliable switching in a very small space. This problem becomes greater when a double pole snap switch with two bridging members is involved. In such a case, for proper operation the movable bridging members must be electrically and mechanically independent of each other. If spring bridging members are used, it is important that they not be pressed against any part of the switch in such a way as to interfere with their freedom of movement.

It is among the objects of this invention to provide a double pole snap switch which is very small, which has a minimum of parts, which has a simplified and space-saving construction, in which the movable bridging contacts will not bind, and in which the switching elements operate independently of each other.

In accordance with this invention, a pivot post projects from one side of an insulating base near its edge, and two laterally spaced pairs of fixed contacts also project from that side. The contacts of each pair are located different distances from the post and preferably are spaced apart along lines radiating from the post. A trigger of special shape is oscillatably mounted on the post. Between the trigger and the base a switching arm also is oscillatably mounted on the post. A torsion spring connects the trigger with the arm for swinging the arm when the trigger is actuated. Carried by the arm, between it and the base, are two bridging spring contacts that are positioned to be moved forward between the fixed contacts when the arm is swung forward. Each spring contact is formed to slidably engage the sides of both adjacent fixed contacts when it is moved forward. It is substantially V-shape, with its narrow front end or apex disposed between a pair of the fixed contacts and with its flaring rear end adapted to engage the sides of those contacts when the switch is closed. The switching arm preferably is provided with holes for receiving projections on the spring contacts to connect them together. The switching arm always engages the ends of the fixed contacts so that it cannot press the spring contacts against the base and cause them to bind. The side Wall of the switch preferably is formed from a band of metal that is wrapped around the base and connected to it by ears projecting from the strip through holes in the base.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. l is a plan View of my double pole snap switch in off position; Fig. 2 is a similar view, but in on position; Fig. 3 is a view of the outside of the base; Fig. 4 is a view similar to Fig. 1, but with the trigger and arm broken away; Fig. 5 is a vertical section taken on the line V-V of Fig. 2; and Figs. 6 and '7 are side views of the metal strips from which the spring contacts and side wall, respectively, are formed.

Referring to the drawings, an insulating base I, which is more or less circular, has a small radially projecting portion 2, near which is mounted a pivot post 3 that extends upward from the base. The post has an integral collar that engages the upper surface of the base, while the lower end of the post is expanded below the base to rivet the post in place. Two pairs of fixed contacts I and 5 are mounted on the base. Each contact has a cylindrical head that projects from the base substantially the same distance as the pivot pin collar. As shown in Fig. 5, each contact extends down through the base and through a metal terminal 6, against which it is upset to hold the contact head and the terminal against the opposite sides of the base. Each pair of contacts are spaced apart different distances from the pivot post, preferably along a line radiating from it, the two pairs of contacts being located along two different lines a few degrees apart as shown in Fig. 4.

Mounted on the pivot post directly above its collar, for movement in a short arc around the post, is a fan shape switching arm I made of insulating material. This arm rests and slides on top of the fiat upper surfaces of the two pairs of fixed contacts. Also mounted on the pivot post in the same manner above the arm is a trigger 8 which has a U-shape body, the lower part of which engages the switching arm and the upper part of which engages the upset upper end of the post. The upper part of the trigger extends out over arm I and is provided with upright lugs 9 that are adapted to straddle a conventional actuating member that can be swung back and forth by the control shaft of a rheostat (not shown) to which the switch usually is attached. The movement of the trigger is limited by its lateral cars which strike the side wall Iil of the switch. The trigger is operatively connected to the switching arm by a torsion spring ll of well known form which, when the trigger is swung from one end of its path of movement to the other, snaps the arm in'the'opposite direction.

The movement of the switching arm is limited by the side wall of the switch. The torsion spring presses the arm against the fiat tops of the fixed contacts to steady it.

The switch side wall H is not formed by means of a metal can or ring, as is the usual practice, but is formed from a band of metal which has been wrapped around the edge of the insulating base I The lower edge of this band, which originally is straight as shown in Fig. '7, is provided at its opposite ends with tongues l5 that are bent under the lower surface of the base as shown in Fig. 3 and then up through a slot 16 in the base near a point on its edge diametrically opposite to projection 2. The upper ends of the tongues are bent down over the upper surface of the base to lock them and to hold the opposite ends of the metal band next to each other. The lower edge of the band also is provided with another pair of tongues I! which extend through slots [8 in the base at opposite sides of its projection 2. Thus, no riveting of the side wall in place is required. Another advantage of using such a band is that the side wall can be deformed to conform to the periphery of the base, which therefore can be irregular and need extend outward at any given point no farther than absolutely necessary. Such an outward extension that is necessary is formed by projecting portion 2. The over-all size of the switch thus can be small enough to permit tongues [9 on the upper edge of the side wall to be fastened to a small rheostat.

With the switching arm 1 in its off position, it is provided about midway between fixed contacts 4 with a rectangular hole 21. Projecting more or less loosely up into this hole is a pair of cars 22 integral with a bridging contact 23 whose thickness is less than the distance between the arm and base. The bridging contact is formed from a narrow resilient strip of metal, originally straight as shown in Fig. 6, that is bent back upon itself into a substantially V- shape. Preferably, as shown in Fig. 4, the apex or narrow front end of the bridging contact is U-shape with spaced parallel sides, from which the ears 22 project up into the overlying arm hole 2|. The rest of the contact flares rearwardly and the rear ends of the strip are spaced apart farther than the fixed contacts 4 that it is to engage when moved forward. It will be seen that in the off position of the switch the front end of the spring contact 23 extends between fixed contacts 4 and across a line connecting their centers. This permits the switch to be made very small, because the bridging contact in the off position only has to project a short distance behind the fixed contacts, even though it is long enough to have the desired resiliency.

The switching arm 1 also is provided with a second rectangular hole 25 which, when the switch is in off position, is between the other pair of fixed contacts 5. Projecting into this hole are the spaced ears 26 of another spring bridging contact 21 shaped the same as bridging contact 23. The front portion of contact 21 extends between fixed contacts 5. The torsion spring II is attached to the switching arm between the two bridging contacts.

When the trigger is actuated to swing the switching arm forward toward the opposite side of the switch, the spring contacts 23 and 2'! are snapped forward between the respective pairs of fixed contacts 4 and. 5 far enough for the diverging rear ends of each springcontact to engage the sides of both adjacent fixed contacts and to slide a short distance across them while being pressed toward each other thereby. Sliding engagement of the bridging contacts with the fixed contacts insures that the contact surfaces will remain clean. As the bridging contacts are connected to the switching arm in front of the portions of those contacts that engage the fixed contacts, the bridging contacts are pulled into engagement with the fixed contacts. This produces more equal contact pressure between each of the flexible parts of each bridging contact and the adjoining fixed contact than if the bridging contacts were pushed into circuit-closing position. It also helps reduce the size of the switch.

It will be observed that the flexible parts of each bridging contact are bent at different angles to cars 22. This is done in order to insure simultaneous engagement of the bridging contact with both of the cooperating fixed contacts, and to obtain proper contact pressure distribution. The resiliency of the bridging contacts assures tight engagement with the fixed contacts, whereby both pairs of fixed contacts always will be bridged when the switch is turned on.

The bridging contacts, not being pressed against the base by the switching arm, can float and freely adjust themselves to the fixed contacts without binding. The switching arm does not touch the contact faces of the fixed contacts, on which it might deposit insulating material.

The snap switch disclosed herein has been described, for the sake of convenience, as if one were looking down into it in Figs. 1 to 4. Nevertheless, it should be understood that the switch may be mounted with its base I vertical or at the top of the unit.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A double pole snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of fixed contacts projecting from said side of the base and spaced apart along a line radiating from the post, a second pair of fixed contacts projecting from said side of the base and spaced apart along another line radiating from said post, said contacts having fiat end surfaces parallel to said base, a trigger oscillatabl mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base and provided with a polygonal hole located between each pair of contacts while the switch is open, a torsion spring connecting the trigger with the arm between the two pairs of contacts and constantly pressing it against said end surfaces of both pairs of the contacts, said spring being formed to swing the arm back and forth across the contacts when the trigger is actuated, and a pair of bridging spring contacts disposed loosely between the base and arm and each formed from a resilient strip of metal bent to provide a narrow front end and free diverging rear ends, said front end of each strip having projecting means extending loosely through one of said arm holes to hold the spring contact with its front end between the adjacent pair of fixed contacts, and the free ends of each spring contact being farther apart than the adjacent pair of fixed contacts and being adapted to be pressed toward each other by the fixed contacts when the spring contact is moved forward between them.

2. A double pole snap switch comprising an insulating base, a pivot post projecting from one side of the base near one edge, a pair of fixed contacts projecting from said side of the base and spaced apart along a, line radiating from the post, a second pair of fixed contacts projecting from said side of the base and spaced apart along another line radiating from said post, said contacts having fiat end surfaces parallel to said base, a trigger oscillatably mounted on the post, a switching arm oscillatably mounted on the post between the trigger and base and provided with a rectangular hole located between each pair of contacts while the switch is open, a torsion spring connecting the trigger with the arm between the two pairs of contacts and constantly pressing it against said end surfaces of both pairs of the contacts, said spring being formed to swing the arm back and forth across the contacts when the trigger is actuated, and a pair of bridging spring contacts disposed loosely between the base and arm and each formed from a resilient strip of metal bent upon itself to provide a U-shape front portion having spaced parallel sides joined to the front ends of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,177,284 Schellenger Oct. 24, 1939 2,235,366 Haselwood Mar. 18, 1941 2,286,162 Schellenger June 9, 1942 2,304,479 Schellenger Dec. 8, 1942 2,419,072 Hall Apr. 15, 1947 2,524,784 Franks et al. Oct. 10, 1950 FOREIGN PATENTS Number Country Date 24,003 Great Britain Oct. 17, 1910 

